Model Prediction Control Scheme of Wind Farm with Energy Storage for Frequency Support

Abstract

The flexible control characteristic of energy storage system makes it have an advantage in participating in grid frequency regulation. The combination of wind power and energy storage has the effect of synergistic enhancement in providing frequency support. However, traditional PID controllers are difficult to achieve coordinated control of wind farms and energy storage. To address this issue, a model predictive control (MPC) based scheme of wind farm with energy storage system for frequency support is proposed. The MPC controller optimizes the power reference for each offshore wind turbine as well as the energy storage system, with the objective of minimizing the grid frequency deviation. In the MPC design, power constraints for wind turbines that adapt various wind speeds are considered, thereby ensuring the stable operation of wind turbines during the frequency support. Meanwhile, state of charge (SoC) constraints for the energy storage system is also proposed to extend its life. What's more, the moving horizon estimation (MHE) is introduced to estimate the grid power imbalance. The results show that the proposed scheme can effectively improve the performance of the grid frequency.